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Hexanchiformes
The Hexanchiformes are the order consisting of the most primitive types of sharks, and numbering just seven extant species. Fossil sharks that were apparently very similar to modern sevengill species are known from Jurassic specimens. Hexanchiform sharks have only one dorsal fin, either six or seven gill slits, and no nictitating membrane in the eyes. Shark teeth similar to those modern hexanchids are known from Devonian deposits in Antarctica and Australia, as well as Permian deposits in Japan. If these are in fact hexanchids, this may be the only extant order of elasmobranchs to have survived after the Permian extinction (and by extension, the oldest extant order of elasmobranchs). The frilled sharks of the genus ''Chlamydoselachus'' are very different from the cow sharks, and have been proposed to be moved to a distinct order, Chlamydoselachiformes. Classification Living species *Family Chlamydoselachidae Garman 1884 (frilled sharks) **''Chlamydoselachus'' Garman, 1884 ** ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shark
Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha (or Selachii) and are the sister group to the rays. However, the term "shark" has also been used to refer to all extinct members of Chondrichthyes with a shark-like morphology, such as hybodonts and xenacanths. The oldest modern sharks are known from the Early Jurassic. They range in size from the small dwarf lanternshark (''Etmopterus perryi''), a deep sea species that is only in length, to the whale shark (''Rhincodon typus''), the largest fish in the world, which reaches approximately in length. Sharks are found in all seas and are common to depths up to . They generally do not live in freshwater, although there are a few known exceptions, such as the bull shark and the river shark, which can be found in both seawater and fresh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frilled Shark
The frilled shark (''Chlamydoselachus anguineus'') and the southern African frilled shark (''Chlamydoselachus africana'') are the two extant species of shark in the family '' Chlamydoselachidae''. The frilled shark is considered a living fossil, because of its primitive, anguilliform (eel-like) physical traits, such as a dark-brown color, amphistyly (the articulation of the jaws to the cranium), and a –long body, which has dorsal, pelvic, and anal fins located towards the tail. The common name, ''frilled shark'', derives from the fringed appearance of the six pairs of gill slits at the shark's throat. The two species of frilled shark are distributed throughout regions of the Atlantic and the Pacific oceans, usually in the waters of the outer continental shelf and of the upper continental slope, where the sharks usually live near the ocean floor, near biologically productive areas of the ecosystem. To live on a diet of cephalopods, smaller sharks, and bony fish, the frilled s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chondrichthyes
Chondrichthyes (; ) is a class that contains the cartilaginous fishes that have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fishes'', which have skeletons primarily composed of bone tissue. Chondrichthyes are jawed vertebrates with paired fins, paired nares, scales, and a heart with its chambers in series. Extant chondrichthyes range in size from the 10 cm (3.9 in) finless sleeper ray to the 10 m (32 ft) whale shark. The class is divided into two subclasses: Elasmobranchii (sharks, rays, skates, and sawfish) and Holocephali ( chimaeras, sometimes called ghost sharks, which are sometimes separated into their own class). Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates. Anatomy Skeleton The skeleton is cartilaginous. The notochord is gradually replaced by a vertebral column during development, except in Holocephali, where the notochord stays intact. In some deepwat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crassodontidanidae
Crassodontidanidae is a family of extinct cow sharks that lived from the Early Jurassic to the Early Cretaceous. It contains three genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...: '' Crassodontidanus'', '' Notidanoides'', and '' Pachyhexanchus''. References {{Taxonbar, from1=Q111600758, from2=Q18349174, irmng=11911783 Jurassic sharks Cretaceous sharks Shark families Prehistoric cartilaginous fish families Sinemurian first appearances Hexanchiformes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cow Shark
Cow sharks are a shark family, the Hexanchidae, characterized by an additional pair or pairs of gill slits. Its 37 species are placed within the 10 genera: ''Gladioserratus'', ''Heptranchias'', ''Hexanchus'', ''Notidanodon'', ''Notorynchus'', ''Pachyhexanchus'', ''Paraheptranchias'', ''Pseudonotidanus'', ''Welcommia'', and ''Weltonia''.Compagno, L., Dando, M. and Fowler, S. ''Sharks of the World''. Princeton Field Guides Cow sharks are considered the most primitive of all the sharks, as their skeletons resemble those of ancient extinct forms, with few modern adaptations. Their excretory and digestive systems are also unspecialized, suggesting they may resemble those of primitive shark ancestors. A possible hexanchid tooth is known from the Permian of Japan, making the family a possible extant survivor of the Permian-Triassic extinction. Their most distinctive feature, however, is the presence of a sixth, and, in two genera, a seventh, gill slit, in contrast to the five found in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Southern African Frilled Shark
The southern African frilled shark (''Chlamydoselachus africana'') is a species of shark in the family Chlamydoselachidae, described in 2009. It is found in the deep waters off southern Angola to southern Namibia. This species is difficult to distinguish from the better-known frilled shark (''C. anguineus''), but is smaller at maturity and differs in several proportional measurements including head length and mouth width. It seems to be a specialized predator of smaller sharks, using its flexible jaws and numerous needle-like, recurved teeth to capture and swallow them whole. Reproduction is presumably aplacental viviparous, as with the other member of its family. Taxonomy The frilled shark (''C. anguineus'') was long thought to be the only extant member of its genus and family. The existence of a second ''Chlamydoselachus'' species off southern Africa was first suspected from a specimen caught off Lüderitz, Namibia in February 1988, by the South African research ship FRS ''A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlamydoselachus
''Chlamydoselachus'' is a genus of sharks and the sole extant member of the family (biology), family Chlamydoselachidae, in the order (biology), order Hexanchiformes. It contains two extant and several extinct species. The most widely known species still surviving is the frilled shark (''Chlamydoselachus anguineus''). It is known as a living fossil, along with ''Chlamydoselachus africana'', also known as the southern African frilled shark, which is only found along coastal areas of South Africa. The only two extant species of this genus are deep-sea creatures which are typically weakened in areas closer to the surface. Species * ''Southern African frilled shark, Chlamydoselachus africana'' David A. Ebert, Ebert & Leonard Compagno, Compagno, 2009 (southern African frilled shark) * ''Frilled shark, Chlamydoselachus anguineus'' Samuel Garman, Garman, 1884 (frilled shark) * †''Chlamydoselachus bracheri'' Pfeil, 1983 * †''Chlamydoselachus fiedleri'' Pfeil, 1983 * †''Chlamydosela ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of the Mesozoic, Mesozoic Era and is named after the Jura Mountains, where limestone strata from the period were first identified. The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic magmatic province, Central Atlantic Magmatic Province. The beginning of the Toarcian Stage started around 183 million years ago and is marked by an extinction event associated with widespread Anoxic event, oceanic anoxia, ocean acidification, and elevated temperatures likely caused by the eruption of the Karoo-Ferrar, Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear boundary with the Cretaceous and i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlamydoselachidae
''Chlamydoselachus'' is a genus of sharks and the sole extant member of the family Chlamydoselachidae, in the order Hexanchiformes. It contains two extant and several extinct species. The most widely known species still surviving is the frilled shark (''Chlamydoselachus anguineus''). It is known as a living fossil, along with ''Chlamydoselachus africana'', also known as the southern African frilled shark, which is only found along coastal areas of South Africa. The only two extant species of this genus are deep-sea creatures which are typically weakened in areas closer to the surface. Species * '' Chlamydoselachus africana'' Ebert & Compagno, 2009 (southern African frilled shark) * '' Chlamydoselachus anguineus'' Garman, 1884 (frilled shark) * †'' Chlamydoselachus bracheri'' Pfeil, 1983 * †'' Chlamydoselachus fiedleri'' Pfeil, 1983 * †'' Chlamydoselachus garmani'' Welton, 1983 * †''Chlamydoselachus goliath ''Rolfodon goliath'' is an extinct species of large frilled ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mcmurdodontidae
''Mcmurdodus'' is an extinct genus of sharks and the sole member of the family Mcmurdodontidae, in the order Hexanchiformes The Hexanchiformes are the order consisting of the most primitive types of sharks, and numbering just seven extant species. Fossil sharks that were apparently very similar to modern sevengill species are known from Jurassic specimens. Hexanchi .... It contains two extinct species.Ginter, M. & Hampe, O. & Duffin, C.J. (2010) Handbook of Paleoichthyology, Vol. 3D: Chondrichthyes Paleozoic Elasmobranchii: Teeth Verlag Dr. Friedrich Pfeil, pp. 168, 154 fig., 4 Tab. Species * '' Mcmurdodus featherensis'' White, 1968 * '' Mcmurdodus whitei'' Turner, & Young, 1987 References {{Taxonbar, from=Q18358508 Devonian sharks Hexanchiformes Prehistoric fish of Australia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orthacodontidae
Orthacodontidae is an extinct family of sharks in the order Synechodontiformes. It contains twelve species within three genera. Some authors included it into Hexanchiformes or Lamniformes. Species * '' Occitanodus'' Guinot, Cappetta & Adnet, 2014 ** '' Occitanodus sudrei'' Guinot, Cappetta & Adnet Adnet is a town in the district of Hallein, in the Austrian state of Salzburg. It is famous for its marble and there is a marble museum in the middle of the town. Geography Adnet is situated near Hallein in the metropolitan area of Salzburg. Urba ..., 2014 * '' Orthacodus'' Woodward, 1889 ** '' Orthacodus longidens'' Agassiz, 1843 * '' Sphenodus'' Agassiz, 1843 ** '' Sphenodus alpinus'' Gümbel, 1861 ** '' Sphenodus longidens'' Agassiz, 1843 ** '' Sphenodus lundgreni'' Davis, 1890 ** '' Sphenodus macer'' Quenstedt, 1852 ** '' Sphenodus nitidus'' Wagner, 1862 ** '' Sphenodus planus'' Agassiz, 1843 ** '' Sphenodus rectidens'' Emmons, 1858 ** '' Sphenodus robustidens'' Seguenza, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elasmobranchii
Elasmobranchii () is a subclass of Chondrichthyes or cartilaginous fish, including sharks (superorder Selachii), rays, skates, and sawfish (superorder Batoidea). Members of this subclass are characterised by having five to seven pairs of gill clefts opening individually to the exterior, rigid dorsal fins and small placoid scales on the skin. The teeth are in several series; the upper jaw is not fused to the cranium, and the lower jaw is articulated with the upper. The details of this jaw anatomy vary between species, and help distinguish the different elasmobranch clades. The pelvic fins in males are modified to create claspers for the transfer of sperm. There is no swim bladder; instead, these fish maintain buoyancy with large livers rich in oil. The definition of the clade is unclear with respect to fossil chondrichthyans. It has been used by different authors as equivalent to Neoselachii (the clade including modern sharks and rays and their last common ancestor) or for al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
